1. Field of the Invention
The invention relates in general to child-resistant closures and in particular to a closure assembly including inner and outer nested caps, the outer cap having an aperture formed therein to permit visual alignment of the caps for easy removal.
2. Description of the Prior Art
Two piece child-resistant closures are known in the art in a variety of specific forms. Typically, such closure assemblies comprise two nested cap members, each cap including a disc-shaped panel and an annular skirt depending from the periphery of the panel. The inside wall of the inner cap skirt includes thread-engaging means for cooperating with a threaded container. Retention means are provided on the cap members for retaining the inner member within the outer member, allowing free relative rotational movement and limited axial movement between the two members. Only the outer cap member or shell is accessible for manipulation when the closure assembly is threaded into engagement on a container.
Typically, the cap members include complementary lugs which positively engage for transmission of torque between the two members when the outer member is rotated in a closure tightening direction, but which normally cam or ratched past each other when the outer cap member is rotated in an opposite, closure removal direction. Various special manipulations, which manipulations are beyond the abilities of small children, are required to bring driving lugs into engagement with cooperating driven lugs for transmission of torque in the closure removal direction. In the common "press and turn" two-member closure, resilient means normally separating driving lugs from the driven lugs are overcome by simultaneously pressing and turning the outer cap member. Such closures are disclosed in U.S. Pat. Nos. 3,795,338 and 3,857,505.
U.S. Pat. No. 4,011,960 to Mauvernay et al. discloses a closure assembly comprising two nested closure members which are relatively axially movable between two predetermined positions. In a child-resistant first position, the closure members can rotate freely relative to each other. In the second position, an upstanding projection from the inner cap member panel engages a correspondingly-shaped aperture formed through the outer cap member panel. In this second position, the engagement of the projection in the aperture provides for transmission of removal torque from the outer member to the inner member. However, after the closure is manipulated to the second position, allowing for removal of the closure, it does not automatically return to the child-resistant first position.